nixos/hardware/printers: fix empty ppdOptions

with lib;

let

  cfg = config.hardware.printers;

  ppdOptionsString = options: optionalString (options != {})

    (concatStringsSep " "

      (mapAttrsToList (name: value: "-o '${name}'='${value}'") options)

    );

  ensurePrinter = p: ''

    ${pkgs.cups}/bin/lpadmin -p '${p.name}' -E \

      ${optionalString (p.location != null) "-L '${p.location}'"} \

      ${optionalString (p.description != null) "-D '${p.description}'"} \

      -v '${p.deviceUri}' \

      -m '${p.model}' \

      ${ppdOptionsString p.ppdOptions}

  ensurePrinter = p: let

    args = cli.toGNUCommandLineShell {} ({

      p = p.name;

      v = p.deviceUri;

      m = p.model;

    } // optionalAttrs (p.location != null) {

      L = p.location;

    } // optionalAttrs (p.description != null) {

      D = p.description;

    } // optionalAttrs (p.ppdOptions != {}) {

      o = mapAttrsToList (name: value: "'${name}'='${value}'") p.ppdOptions;

    });

  in ''

    ${pkgs.cups}/bin/lpadmin ${args} -E

  '';

  ensureDefaultPrinter = name: ''

    ${pkgs.cups}/bin/lpadmin -d '${name}'

  '';